Fixing the Plumbing
Chevron restores life to withering wetlands on the upper Texas coast.
By Wendee Holtcamp
On the southeastern edge of Texas, near the Louisiana border, Chevron has partnered with TPWD, restoring coastal wetlands in the Lower Neches Wildlife Management Area, reworking "plumbing" once damaged by decades of landscape changes, including sinking land and intruding saltwater. The ducks have already started to arrive.
Chevron acquired a Port Arthur refinery that had operated from 1902 to 1995, and had damaged the marshes and emitted toxins including oil, volatile organic compounds, lead and chromium. A 2005 Natural Resources Damages settlement ordered Chevron to clean up the toxics at the refinery site, which it has done, and to restore some of the area's coastal wetlands.
"They had this big project, and we had this big need," says Mike Rezsutek, TPWD wetlands and waterfowl specialist. "We own a site just outside of Bridge City that at one time was a complete stand of emergent marsh vegetation. Through the years all of that marsh started to die off and it became a self-feeding cycle. The more that died, the more that eventually opened into a shallow water flat with little productivity."
Hurricanes Rita and Katrina brought the importance of coastal wetlands to national attention. Coastal marshes provide nursery grounds for shrimp, crab and some 90 percent of commercially harvested fish and shellfish. On the upper Texas coast, the combination of sea level rise and land subsidence due to oil and gas extraction results in intense erosion – a relative loss of 1.2 cm in elevation per year.
That may not sound like much, but on the upper Texas coast alone, it translates into 455 acres of brackish and saltwater coastal marsh lost every year. Combined with pollution and habitat conversion, coastal wetlands are in dire straits.
After consulting with TPWD, Chevron decided it would try to restore the Lower Neches WMA Old River Unit for its mitigation project. "If you look at old historical photos going back to the '40s, you can see there was wetland across this whole area," explains Jerry Hall, Chevron environmental scientist and project manager. "Through the 1950s, '60s and '70s, saltwater began to move into the area. What was an intact marsh in '43, in 2005 was open water."
Chevron engineers hauled in 200,000 cubic yards of dredge material, piling it into circular mounds and long terraces. Next, they hand-planted marsh vegetation on the mounds and terraces. When they finished in summer 2008, they had restored 85 acres of estuarine emergent marsh and 30 acres of upland wet prairie. They also plugged up a canal on the Old Bailey Canal Road (aka Lake Street) that brought excess saltwater into the marsh. These hydrological fixes benefit several thousand acres of surrounding wetlands.
Chevron will monitor the wetland for three years, and then TPWD will manage the site in perpetuity. The site will be open to the public for birdwatching, waterfowl hunting, fishing and other activities.
Post-hurricane update: "We had some die-off of the plants on the higher elevations from salt water, but the marsh plants are doing pretty well overall. Hurricane Ike caused some damage, but didn't completely destroy the restoration, although the long-term impacts are yet to be seen," says Rezsutek.